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The Single UNIX &reg; Specification, Version 2<br>
Copyright &copy; 1997 The Open Group

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<h4><a name = "tag_000_007_038">&nbsp;</a>NAME</h4><blockquote>
isatty - test for a terminal device
</blockquote><h4><a name = "tag_000_007_039">&nbsp;</a>SYNOPSIS</h4><blockquote>
<pre><code>

#include &lt;<a href="unistd.h.html">unistd.h</a>&gt;

int isatty(int <i>fildes</i>);
</code>
</pre>
</blockquote><h4><a name = "tag_000_007_040">&nbsp;</a>DESCRIPTION</h4><blockquote>
The
<i>isatty()</i>
function tests whether
<i>fildes</i>,
an open file descriptor, is associated with a terminal device.
</blockquote><h4><a name = "tag_000_007_041">&nbsp;</a>RETURN VALUE</h4><blockquote>
The
<i>isatty()</i>
function returns 1 if
<i>fildes</i>
is associated with a terminal; otherwise it returns 0
and may set
<i>errno</i>
to indicate the error.
</blockquote><h4><a name = "tag_000_007_042">&nbsp;</a>ERRORS</h4><blockquote>
The
<i>isatty()</i>
function may fail if:
<dl compact>

<dt>[EBADF]<dd>
The
<i>fildes</i>
argument is not a valid open file descriptor.

<dt>[ENOTTY]<dd>
The
<i>fildes</i>
argument is not associated with a terminal.

</dl>
</blockquote><h4><a name = "tag_000_007_043">&nbsp;</a>EXAMPLES</h4><blockquote>
None.
</blockquote><h4><a name = "tag_000_007_044">&nbsp;</a>APPLICATION USAGE</h4><blockquote>
The
<i>isatty()</i>
function does not necessarily indicate that a human being is available for
interaction via
<i>fildes</i>.
It is quite possible that non-terminal devices are connected to
the communications line.
</blockquote><h4><a name = "tag_000_007_045">&nbsp;</a>FUTURE DIRECTIONS</h4><blockquote>
None.
</blockquote><h4><a name = "tag_000_007_046">&nbsp;</a>SEE ALSO</h4><blockquote>
<i><a href="unistd.h.html">&lt;unistd.h&gt;</a></i>.
</blockquote><h4>DERIVATION</h4><blockquote>
Derived from Issue 1 of the SVID.
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UNIX &reg; is a registered Trademark of The Open Group.<br>
Copyright &copy; 1997 The Open Group
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